search for: obattempts

..."jj" of length length(dim(a)). The elements of jj are vectors of indexes. How do I use do.call() to extract a[ jj[[1]], jj[[2]], jj[[3]], ...] ? Toy example follows: a <- matrix(1:30,5,6) jj <- list(5:1,6:1) I want the following a[ jj[[1]],jj[[2]] ] How do I do this? OBAttempts: do.call("[",list(a,jj)) do.call("[",c(a,jj)) do.call("[",list(a,unlist(jj))) Of course, the one that works is do.call("[",list(a,jj[[1]],jj[[2]])) but I don't know how long jj is apriori so this won't do. -- Robin Hankin Uncertainty Analyst Sou...

Hi everyone. I'm playing with aperm(): a <- 1:24 dim(a) <- c(2,3,2,2) permutation <- c(1,2,4,3) b <- aperm(a,permutation) So if my understanding is right, a[1,3,2,1] == b[c(1,3,2,1)[permutation] ] but this isn't what I want because the RHS evaluates to a vector, and I am trying to identify a single element of b. How do I modify the RHS to give what I want? Following

...1, 2, 5, 6, 9,10, 3, 4, 7, 8,11,12, 13,14,17,18,21,22, 15,16,19,20,23,24, 25,26,29,30,33,34, 27,28,31,32,35,36 )),6,6) So identical(x[,,1] , y[1:2,1:2]) identical(x[,,2] , y[3:4,1:2]) [snip] identical(x[,,9] , y[5:6,5:6]) all return TRUE. OBattempts: (i) dim(x) <- c(4,9);x <- t(x) ; dim(x) <- c(6,6) ; y <- x (ii) y <- aperm(x,c(2,1,3)) ; dim(y) <- c(6,6) Any genius out there with some ideas? -- Robin Hankin Uncertainty Analyst Southampton Oceanography Centre SO14 3ZH tel +44(0)23-8059-7743 initialDOTsurname at soc.soton...

...vector c(1,2,3,1). As per yesterday, I can use do.call(): a[1,2,3,1] == do.call("[",c(list(a),c(1,2,3,1))) Now how do I apply the above technique (or indeed any other technique!) to get a[1,2,3,] [1] 37 101 165 229 from a vector like c(1,2,3,0) or c(1,2,3,NULL) or c(1,2,3,NA)? OBattempts: do.call("[",c(list(a),c(1,2,3))) do.call("[",c(list(a),c(1,2,3),NULL)) do.call("[",c(list(a),c(1,2,3,NULL))) do.call("[",c(list(a),c(1,2,3,","))) none of these give what I want. Anyone? -- Robin Hankin Uncertainty Analyst Southampton Oceanograp...